Curable resin systems are widely known and have a wide range of uses in a variety of technical fields. These systems function by reaction between resin molecules and curing agents. Upon activation, e.g. by mixing together or by heating, functional groups on the curing agent react with functional groups on the resin molecule to form an extended polymeric network, which is the process known as curing.
The resulting cured resin has physical properties which are largely or entirely dictated by the choice of resin, the choice of curing agent and the curing regime employed. A wide variety of physical properties can be obtained by altering one or more of these variables.
A particularly useful physical property is for the cured resin to be mechanically tough and able to withstand an impact without brittle fracture. Such resins are particularly useful when involved in the manufacture of a structure.
However, it is known that cured resins which are tough generally tend to have a low glass transition temperature, which can make them unsuitable for use in structures. Known methods of increasing the glass transition temperature, generally involve the material becoming more brittle, which is again not appropriate for use in structures. Additionally, known methods of toughening a brittle resin usually also reduce the glass transition temperature.
It would therefore appear that cured resin systems which are both mechanically tough and yet have a high glass transition temperature, so that they can be used in structural applications, are not readily achievable with known systems.